[xubuntu] Java: Is there a reset button somewhere?

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I have been trying to get JMRI 3.0 (a Java based model railroad program) to work on my computer running Xubuntu 12.04. In trying to get something squared away with the program's ability to recognize USB port connected devices I tried several things including installing probably more version of Java than I should have, and I would like to just hit the "reset" button if there is one.
I have the Oracle version of Java, I think (but I don't know how to confirm this) and aldo both OpenJDK Java Runtime 6 and 7. If I can zonk all of them in one fell swoop and then just reinstall one of the
(Hardware)

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